use enumflags2::BitFlags;
use log::error;
use speedy::{Readable, Writable};

use crate::rtps::{
    messages::submessages::submessages::SubmessageHeader,
    structure::{
        guid::EntityId,
        sequence_number::{SequenceNumber, SequenceNumberSet},
    },
    Submessage, SubmessageBody,
};
use super::{
    submessage::{HasEntityIds, WriterSubmessage},
    submessage_flag::GAP_Flags,
    submessage_kind::SubmessageKind,
};
/// This Submessage is sent from an RTPS Writer to an RTPS Reader and
/// indicates to the RTPS Reader that a range of sequence numbers
/// is no longer relevant. The set may be a contiguous range of
/// sequence numbers or a specific set of sequence numbers.
#[derive(Debug, PartialEq, Eq, Clone, Readable, Writable)]
pub struct Gap {
    /// Identifies the Reader Entity that is being informed of the
    /// irrelevance of a set of sequence numbers.
    pub reader_id: EntityId,

    /// Identifies the Writer Entity to which the range of sequence
    /// numbers applies.
    pub writer_id: EntityId,

    /// Identifies the first sequence number in the interval of
    /// irrelevant sequence numbers
    pub gap_start: SequenceNumber,

    /// Identifies the last sequence number in the interval of irrelevant
    /// sequence numbers.
    ///
    /// Identifies an additional list of sequence numbers that are
    /// irrelevant.
    pub gap_list: SequenceNumberSet,
}

impl Gap {
    pub fn create_submessage(self, flags: BitFlags<GAP_Flags>) -> Option<Submessage> {
        let submessage_len = match self.write_to_vec() {
            Ok(bytes) => bytes.len() as u16,
            Err(e) => {
                error!("Reader couldn't write GAP to bytes: {}", e);
                return None;
            }
        };

        Some(Submessage {
            header: SubmessageHeader {
                kind: SubmessageKind::GAP,
                flags: flags.bits(),
                content_length: submessage_len,
            },
            body: SubmessageBody::Writer(WriterSubmessage::Gap(self, flags)),
            original_bytes: None,
        })
    }
}

impl HasEntityIds for Gap {
    fn receiver_entity_id(&self) -> EntityId {
        self.reader_id
    }
    fn sender_entity_id(&self) -> EntityId {
        self.writer_id
    }
}

#[cfg(test)]
mod tests {
    use super::*;

    serialization_test!( type = Gap,
    {
        gap,
        Gap {
            reader_id: EntityId::SEDP_BUILTIN_PUBLICATIONS_READER,
            writer_id: EntityId::SEDP_BUILTIN_PUBLICATIONS_WRITER,
            gap_start: SequenceNumber::from(42),
            gap_list: SequenceNumberSet::new_empty(SequenceNumber::from(7))
        },
        le = [0x00, 0x00, 0x03, 0xC7,
              0x00, 0x00, 0x03, 0xC2,
              0x00, 0x00, 0x00, 0x00,
              0x2A, 0x00, 0x00, 0x00,
              0x00, 0x00, 0x00, 0x00,
              0x07, 0x00, 0x00, 0x00,
              0x00, 0x00, 0x00, 0x00],
        be = [0x00, 0x00, 0x03, 0xC7,
              0x00, 0x00, 0x03, 0xC2,
              0x00, 0x00, 0x00, 0x00,
              0x00, 0x00, 0x00, 0x2A,
              0x00, 0x00, 0x00, 0x00,
              0x00, 0x00, 0x00, 0x07,
              0x00, 0x00, 0x00, 0x00]
    });
}
